Vehicles are equipped with heating, ventilation and air conditioning (HVAC) systems for controlling and maintaining suitable temperatures and humidity level in vehicle passenger compartments. One requirement for an HVAC system may include maintaining coolant temperature above a minimum threshold during operation in cold ambient conditions. Hybrid powertrain systems employing engine stop/start systems may experience a reduction in operation of the engine stop/start system due to a requirement to maintain the coolant temperature above a minimum threshold. This may include engine idling when the vehicle is stopped, which is undesirable. Engine operation when a vehicle is stopped may result in unnecessary charging of a battery for the hybrid powertrain system.